metabolic disorder, 1923, from porphyrin (1910), the ame of the type of chemical which, in imbalance, causes it, from German porphyrin, chemical name, from Greek porphyros "purple" (see purple) + -in (2). Some of the compounds are purple.

any of a group of diseases characterized by the marked overproduction and excretion of porphyrins or of one or another of their precursors. The porphyrins are reddish constituents of heme, the deep red iron-containing pigment of hemoglobin, the oxygen-carrying protein of the red blood cells. The deposition of porphyrin compounds in body tissues, notably the skin, gives rise to a variety of symptoms, the nature of which depends on the specific compound that is abnormally metabolized.